// Copyright (c) 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_MOJO_IPC_MOJO_HANDLE_ATTACHMENT_H_
#define IPC_MOJO_IPC_MOJO_HANDLE_ATTACHMENT_H_

#include "base/files/file.h"
#include "base/macros.h"
#include "build/build_config.h"
#include "ipc/ipc_export.h"
#include "ipc/ipc_message_attachment.h"
#include "mojo/public/cpp/system/handle.h"

namespace IPC {

namespace internal {

    // A MessageAttachment that holds a MojoHandle.
    // * On the sending side, every Mojo handle is a MessagePipe. This is because
    //   any platform files are wrapped by PlatformFileAttachment.
    // * On the receiving side, the handle can be either MessagePipe or wrapped
    //   platform file: All files, not only MessagePipes are wrapped as a
    //   MojoHandle. The message deserializer should know which type of the object
    //   the handle wraps.
    class IPC_MOJO_EXPORT MojoHandleAttachment : public MessageAttachment {
    public:
        explicit MojoHandleAttachment(mojo::ScopedHandle handle);

        Type GetType() const override;

#if defined(OS_POSIX)
        // Returns wrapped file if it wraps a file, or
        // an invalid fd otherwise. The ownership of handle
        // is passed to the caller.
        base::PlatformFile TakePlatformFile() override;
#endif // OS_POSIX

        // Returns the owning handle transferring the ownership.
        mojo::ScopedHandle TakeHandle();

    private:
        ~MojoHandleAttachment() override;
        mojo::ScopedHandle handle_;

        DISALLOW_COPY_AND_ASSIGN(MojoHandleAttachment);
    };

} // namespace internal
} // namespace IPC

#endif // IPC_MOJO_IPC_MOJO_HANDLE_ATTACHMENT_H_
